The high-tech hunt for WWII MIAs (pictures)

Hellcat flag ceremony

AIMELIIK STATE, PALAU--For 70 years, dozens of American airmen have been listed as missing in action after being shot down over this South Pacific nation during World War II by the Japanese.

But for the families of some, the long wait to learn their fate has come to an end thanks to the efforts of the BentProp Project, a group of volunteers that for years has been traveling each year to Palau to hunt for the lost planes and the missing men who went down with them.

Late last month, the BentProp project held a flag ceremony to mark the discovery of two planes shot down in 1944, a TBM Avenger and an F6F Hellcat.

During the ceremony for the Hellcat, BentProp founder Pat Scannon (right) remembered the sacrifice made by the plane's pilot, and the years the airman's family has been waiting to learn his fate.

In 2014, BentProp's annual expedition was joined by scientists from the Scripps Institution of Oceanography and the University of Delaware's School of Marine Science and Policy, who brought with them high-tech tools to help in the hunt for the MIAs.

Avenger propeller

This is the front propeller of the TBM Avenger, which was found in the waters off Aimeliik State in Palau on March 24, 2014 thanks to the joint effort of the BentProp Project and scientists from the Scripps Institution of Oceanobgraphy and the University of Delaware's School of Marine Science and Policy.

Remus ready for launch

The key scientific tool the combined teams used during the 2014 mission to find the downed planes was the Remus autonomous underwater vehicle. The $300,000 device is loaded with sensors and scanners and can be programmed to autonomously survey large grids of open water. Among other things, it utilizes side scan sonar, which can generate imagery of the sea bottom regardless of visibility.

Avenger wing

Though the combined BentProp/Scripps/Delaware teams found the Avenger on March 24, 2014, BentProp had been looking for it since 2005, when members of the volunteer organization had first found one of its wings in the mangrove jungle at the edge of Aimeliik. This photo was taken in 2005 when the wing was first discovered.

Murky Avenger

One of the reason many of the lost airplanes have gone unfound for 70 years is that they are located in murky water. In a country known for some of the best scuba diving in the world thanks to the clarity of its waters, that means that few, if any, people have visited the sites where the planes came to rest, and as a result, they remained missing since 1944.

Side scan sonar imagery of Avenger

Although the average person might never recognize anything out of the ordinary in this imagery generated by side scan sonar, experts like Scripps' Terrill can see that it contains something man-made. In this case, it shows the landing gear of the TBM Avenger.

This image that identified the Avenger

BentProp members had been hunting for the Avenger since they first found one of its wings in the Palauan jungles in 2005. In 2014, thanks to new information about where the plane might have ended up, the science teams on the expedition sent one of the Remus AUVs to survey areas off Aimeliik. This is the image that finally showed the airplane and led the teams to scuba dive the site and find the Avenger.

Side scan imagery of Hellcat wing

The teams searching for the Hellcat had gotten nowhere for years. Until, that is, they saw this side scan sonar image. In the lower right hand area of the image, you can see a shape that the scientists eventually identified as the plane's wing.

Belcher jumping to dive LVT

Bill Belcher, a BentProp member and a forensic anthropologist from the Joint POW/MIA Accounting Command (JPAC) dives a site near Peleliu in order to take a closer look at an LVT, an amphibious warfare vehicle that the U.S. Marines used to storm the island in September, 1944. The LVT was sunk, and has been sitting there for 70 years.

LVT today

The turret of the LVT, as seen earlier this month, 75 feet under water off the coast of Peleliu. It is now covered in coral, and to the average person, would almost certainly not be identifiable for what it is.

Three Remuses

During the 2014 expedition, the Scripps and Delaware teams brought a total of three Remus AUVs. Here, the three underwater vehicles are seen in the lab at the Coral Reef Research Foundation in Koror, Palau, where the science teams worked throughout the expedition.

ACDP

This is an acoustic Doppler current profiler, a device used by oceanographers to measure how currents are shifting in the Palauan islands. That's important, Scripps' Terrill said, because ocean behavior in the Western and South Pacific are is a "canary in a coalmine" for ocean behavior elsewhere. Sea level rise has been three times higher in the area than in the West Coast of the United States.

Diving the ADCP

In order to get meaningful data on changes in currents, the ADCP must be placed in the ocean and left there for some time. As a result, Scripps anchored this one on a sea mount near Peleliu. Here, Terrill holds on to the device as he dives into the ocean.

Kemedukl

The Kemedukl is a 40-foot catamaran used by the science teams from Scripps and Delaware and the BentProp Project to seaarch for missing airplanes and the aviators who went down with them. The boat is owned by Dr. Pat Colin of the Coral Reef Research Foundation.

The flag ceremonies held for the Hellcat and Avenger were performed on the boat.

Andy pushing the Remus down

Sometimes the Remus needs a bit of cajoling to do what they're supposed to. During one mission, the vehicle was having trouble submerging. As a result, Scripps development engineer Andy Nager jumped into the water and physically pushed it underwater.

Evan flying a drone

Scripps development engineer Evan Walsh pilots a 3D Robotics aerial drone off the back of the Kemedukl. He was flying the device over the Aimeliik jungles in order to try to get aerial imagery of the area where the Avenger's wing was originally found in 2005.

Probable flight paths

In order to try to determine where a B-24 bomber may have crashed, Scripps scientists came up with probability models based on a number of factors including wind direction, that show where the plane may have gone down. Each colored path represents a different scenario.

Towfish

This device, known a a Towfish, is placed in the water and connected by cable to computer used by the scientists on board the boats. The towfish communicates wirelessly with transponders placed in the water that in turn communicate with the Remus in order to triangulate its location.